FDA pulls high-dose Zofran

The 32 mg, single intravenous (IV) dose of the anti-nausea drug ondansetron (Zofran, GlaxoSmithKline) has been pulled from the market due to potential for serious cardiac risks, the FDA announced in a MedWatch Safety Alert.

The high dose formulation of ondansetron was indicated to prevent chemotherapy-induced nausea and vomiting. Lower doses of the drug are used to treat postoperative nausea and vomiting.

"FDA does not anticipate that removal of the 32-mg intravenous dose of ondansetron currently sold as pre-mixed injections will contribute to a drug shortage of IV ondansetron, as the 32-mg dose makes up a very small percentage of the current market," the FDA said in the statement.

The agency previously issued a Drug Safety Communication in June, warning that 32 mg, single IV doses of ondansetron should be avoided due to the risk of QT interval prolongation, which can lead to torsades de pointes, a potentially fatal arrhythmia.

The FDA continues to recommend an intravenous regimen of 0.15 mg/kg ondansetron administered every 4 hours for three doses to prevent chemotherapy-induced nausea and vomiting.

"Oral dosing of ondansetron remains effective for the prevention of chemotherapy-induced nausea and vomiting. At this time, there is not enough information available for FDA to recommend an alternative single IV dose regimen," the statement said.

The FDA first began investigating the link between ondansetron and cardiac rhythm disorders in September 2011 in collaboration with the drug's manufacturer, GlaxoSmithKline. Preliminary results from that investigation showed a maximum mean difference in QTcF of 20 msec after the 32-mg IV dose. However, mean maximum QTcF difference ater an 8-mg IV dose was 6 msec.

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